Method of forming cutting tools



u e 7 A. w. COCHRAN METHOD OF FORMING CUTTING TOOLS Filed July '13, 1925 TES.

Patented June `7, 1927.

unirse; sra

ALBERT W. COCHRAN, 0F PORTLAND, OREGON.

*,MEVTHOD OF FORMING CUTTING TOOLSV.

Application filed July` 13,

illy invention relates to the torming ot" metal tools with cutting edges by drop orgi ing or by other method. utilizing` compression dies or n'iembers which serve to diminish, in cross section, the blank' of material being formed. 'l have discovered that it a blank oll material, and the dies or members, are sorelatively arranged, that the cutting edge to be termed, .is p .-ced at the parting line between said dies or members, through which the excess material is 'forcedl by the compression, the grain structure in the cutting edge will be elongated transversely, to produce an extremely tough and. strong edge. That is. l have discovered'that 'l can produce a tool with ait'ough edge, such as is produced by hand-haruneringa cutting edge merely by arranging` the die, halves so that the parting` linek terms a continuation of the portion ofthe reces's'ytherein which produces the cutting edge. rlhe arranging of the recesses in the die halves in this manner tends to produce a flow ot the Vexcess material eX- pressed from between said die halves through the portion ot the die which forms said cuttingedge.

The details oit this method and et the die elements are hereinafter described in greater detail, reference being made to the accompanying drawings, in which:V

Fig. l is a diagrammatic section through two die halves, spaced apart, and with a blank of material arranged therein;

Fig. 2 is a similar section showing the die halves as having been compressed, to form the tool and to express the excess material; and v Fig. 3 is a. plan view of the material after being so compressed showing` how the tool is blanked in, and a relatively thin iin ot material is formed thereabout, by the excessfmaterial.

My invention is particularly adapted to drop-'forging operations and the dies user-l therein, although it is also adapted to be used in press work and other dies, or members, which use compression solely, such, tor example. as forming dies and 1lorming rolls. There l refer to compressiondies and compression members, l thus wish to include not only dies used tor drop-forging but also forming dies and forn'iing rolls which do not utilize impact, in addition to compression.

As shown in Fig. l, the two die halves c and Z) are formed to have companion recesses c and d, which are each substantially one- A1925. seriai no.' 43,285.

halt ol the shape ofthe tool to be formed. r`he `parting lines between the recesses, so formed, constitute virtually'a continuation et said recess and'pre't'erably does not diminish, substantially, in thickness. Thus, torerzample', in Fig. 2, the recess formed between said two die halves by the comianion recesses c and d might be said .to terminate' at the lines A-A. and BeB and the remainder' of space outside ot' said lines constitute the parting lines e and f. Thus when fa blank ot material g is vplaced between the die halves, which are spaced apart, the compression of said die halves produces a lin of `material g" about the body [/,2 of the tool being torn'ied, because a blank of material is used which is substantially larger-.than the ultimate tool to be formed. yThus"l the .Jed blank, as shownin Fig. 3,'must nmed Vas torremov'e the entiretin g theretrom. This is done, however, with the ordinary die used to remove a fin from any drop forging. A tool made in this manner must be dressed to remove the scale and also to ysharpen the edge.y The tool, however, is made so as to be substantially the'same size as the ultimate dressed tool, sufficient material being provided merely to permit the scale, caused by the heating of said blank, to be removed and the cuttingr edge to be sharpened. By producing a tool in this manner a cutting edge is provided which has been formed or forged as compared with one which has been milled or ground.

vThe tool which I show in the drawings is used as a router bit in cutting away the eX-r cess material trom stereotype plates and the like, and is the subject of a co-pending application. Tools of this character require a very tough edge because they are driven at a tremendouslyV high rate ot speed which ywears an edge away very quickly and also tends td break oft portions if forced into the work too quickly. Tools similar to these are sold on the market at present, but said tools are ground or milled to size from a blank. By operating one of said tools alongside or' a tool made bv my improved method, I have discovered that the ground or milled tool will not hold an edge more than half as long as one made by my method.

l am aware that it is old to .produce acutting edge such as a razor edge by hand forging, that is. by drawing said edge out with a hammer and thus do not' wish to claim this manner of producing` a cutting edge. My invention is limited entirely to die elements for forming and to the producing of a cutting edge between two compression members, such for example, as the halves ot a die used in drop forging or the halves of a forming die, or formingrolls.

It is to be particularly noted thatthe die members confine the outliow of the excess metal to a point coincident with and extendi ing materiallybeyond the parting line so as to insure that the grain of the metal will be y directly transverse what is to be the cutting edge of the tool in final lorm. By continuing the confinement ot' the metal beyond this parting or subsequent cutting edge of the tool, there is no liability of grain distortion yat such edge.

I claim: 1. The improved method of producing a cutting tool consisting in placing a block of metal between companion dies whose working faces are shaped to form the tool to and including the cutting edge thereof and exitended beyond said cutting edge to conline the How of excess metal in substantial uniformity with the confinement aty the cutting edge, whereby the grain of the metal is elongated through and beyond the cutting edge line to insure that said grain structure will be elongated transversely at the cutting edge line.

2. The improved method ot producing a cutting tool with a curved edge consisting in placing a block ot' .metal of greater cross section than that to be given the tool between companion dies whose working faces are curved and spaced from each other in conformity with the cross section and the curve to be given the tool in the direct-ion of gated in the direction of its taper and towards its edge.

ALBERT w. COCHRAN. 

